APOA4 and cancer: Candidates APOA4, VDBP, A1AT/SERPINA1, and SLPI were selected for initial validation and were measured by ELISA in serum samples from 89 benign and 70 malignant ovarian cancer cases, with the latter grouped into early‐stage (FIGO I and II) and late‐stage (FIGO III and IV) cancers.